Component for plasma processing apparatus, and manufacturing method therefor

ABSTRACT

Particle generation can be suppressed from a thermally sprayed film of yttrium fluoride. A component exposed to plasma in a plasma processing apparatus is provided. The component includes a base and a film. The base is made of aluminum or an aluminum alloy, and an alumite film may be formed on a surface of the base. The film is formed by thermally spraying yttrium fluoride on a surface of the base or on a surface of an underlying layer including a layer provided on the base. A porosity of the film is 4% or less, and an arithmetic mean roughness of a surface of the film is 4.5 μm or less.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Japanese Patent Application Nos. 2014-188695 and 2015-129940 filed on Sep. 17, 2014 and Jun. 29, 2015, respectively, the entire disclosures of which are incorporated herein by reference.

TECHNICAL FIELD

The embodiments described herein pertain generally to a component for a plasma processing apparatus and a manufacturing method therefor.

BACKGROUND

In the manufacture of an electronic device such as a semiconductor device, plasma etching is performed on a processing target object. The degree of accuracy required for the plasma etching is getting higher year by year as the electronic device is getting more miniaturized. To achieve the high accuracy of the plasma etching, particle generation needs to be suppressed.

A processing vessel of a plasma processing apparatus used for this plasma etching is made of a metal such as aluminum. An inner wall surface of the processing vessel is exposed to plasma. Thus, in a plasma processing apparatus, a plasma-resistant film is formed on an inner wall of the processing vessel. Generally, such a film is made of yttrium oxide (yttria).

If this yttrium oxide film is exposed to plasma of a fluorocarbon-based gas, it reacts with active species such as fluorine in the plasma. As a result, the yttrium oxide film is consumed. To solve this problem, it is recently attempted to form the film on the inner wall of the processing vessel with yttrium fluoride. This yttrium fluoride film is formed by thermal spraying, as described in Patent Document 1.

-   Patent Document 1: Japanese Patent Laid-open Publication No.     2013-140950

As higher level of accuracy is required for the plasma etching, it is required to suppress even the particles having small sizes which have been never regarded as problems conventionally. For this purpose, particle generation from the thermally sprayed yttrium fluoride film needs to be further suppressed.

SUMMARY

In one exemplary embodiment, there is provided a component exposed to plasma in a plasma processing apparatus. The component includes a base and a film. The base, for example, is made of aluminum or an aluminum alloy, and an alumite film may be formed on a surface of the base. The film is formed by thermally spraying yttrium fluoride onto the surface of the base or on a surface of an underlying layer including a layer provided on the base. In the component, a porosity of the film is 4% or less, and an arithmetic mean roughness (Ra) of the surface of the film is 4.5 μm or less. The arithmetic mean roughness (Ra) is defined by JIS 60601-1994.

In the component, the film covering the base is a thermally sprayed film of yttrium fluoride. This film has a low porosity and is a dense film having a small specific surface area. Accordingly, a little change in the surface thereof occurs even when it is exposed to the plasma, and, thus, a variation in process performance can be reduced. Therefore, according to this manufacturing method PM, it is possible to form a film capable of suppressing the particle generation.

The component may further include a first intermediate layer which is made of an yttrium oxide film formed by an atmospheric plasma spraying method, and is provided between the base and the film. The component in the plasma processing apparatus may be required to have a high breakdown voltage. However, the thermally sprayed film of yttrium fluoride has a relatively low breakdown voltage. In accordance with the exemplary embodiment, since the first intermediate layer formed by a thermally sprayed film of yttrium oxide is provided as an underlying layer of the film, the multilayered film including the film and the first intermediate layer and having a high breakdown voltage is provided on the base.

The film may not be formed on a region including an edge of the first intermediate layer, but may be formed on the first intermediate layer at an inner side than the region. An adhesive strength of the yttrium fluoride film to the base is relatively low. In accordance with the exemplary embodiment, since the film is not contact with the base at the edge region, peeling of the film can be suppressed.

The component may include a second intermediate layer provided between the first intermediate layer and the film. The second intermediate layer may have a linear expansion coefficient that falls between the linear expansion coefficient of the first intermediate layer and the linear expansion coefficient of the film. In accordance with the exemplary embodiment, the peeling of the film that might be caused by a difference in the linear expansion coefficients between the film and the first intermediate layer can be suppressed. By way of example, the second intermediate layer may be formed of a thermally sprayed film of forsterite or a thermally sprayed film of yttria-stabilized zirconia (YSZ) formed by the atmospheric plasma spraying method. Further, the second intermediate layer may be made of a thermally sprayed film of gray alumina or a thermally sprayed film of alumina formed by the atmospheric plasma spraying method. The multilayered film including the film, the first intermediate layer and the second intermediate layer and having a high breakdown voltage is provided on the base.

The component may include another intermediate layer provided between the base and the first intermediate layer. By way of example, the another intermediate layer can be formed of a thermally sprayed film of gray alumina or a thermally sprayed film of alumina formed by the atmospheric plasma spraying method. In accordance with the exemplary embodiment, the multilayered film including the film, the first intermediate layer and the another intermediate layer and having a high breakdown voltage is provided on the base.

In another exemplary embodiment, there is provided a manufacturing method for the above-described component in the plasma processing apparatus. The manufacturing method includes performing a surface conditioning on a surface of an underlying layer on which a film is to be formed by thermal spraying, and the surface of the underlying layer includes a surface of a base or a surface of a layer formed on the surface of the base; and forming the film on the surface of the underlying layer by thermally spraying yttrium fluoride. In the forming of the film, a slurry containing yttrium fluoride particles having an average diameter ranging from 1 μm to 8 μm is supplied, from a nozzle of a spraying gun configured to jet a flame in a high velocity oxygen fuel spraying method or from a nozzle of a spraying gun configured to discharge a plasma jet in an atmospheric plasma spraying method, to a position distanced apart from the nozzle of the spraying gun toward a downstream side in a direction of a central axis line of the nozzle of the spraying gun or to a position corresponding to a tip end of the nozzle of the spraying gun.

In this manufacturing method, since the film is formed on the surface of the underlying layer on which a surface conditioning is performed, the film has a low surface roughness. Since this film has a small specific surface area, a little change in the surface thereof occurs even when it is exposed to the plasma, and, thus, a variation in process performance can be reduced. Therefore, according to this manufacturing method PM, it is possible to form a film capable of suppressing the particle generation. Further, since the average diameter of the particles contained in the slurry is in the range from 1 μm to 8 μm, aggregation between the particles is suppressed, so that the uniform film can be formed. Moreover, since the average diameter of the particles contained in the slurry is in the range from 1 μm to 8 μm, the film having a high adhesivity between the particles can be formed. In addition, since the slurry is supplied to the aforementioned position, adhesion of the sprayed material to an inner wall of a nozzle of the spraying gun can be suppressed. As a result, spitting can be suppressed. Thus, according to this manufacturing method, it is possible to form a film having a low porosity and a small specific surface area, that is, a highly dense film. Since the formed film is highly dense, it has a high cross sectional hardness. Therefore, according to the present manufacturing method, it is possible to form a film capable of suppressing particle generation.

The high velocity oxygen fuel spraying method may be used in the forming of the film, and the position to which the slurry is supplied may be in the range from 0 mm to 100 mm from the tip end of the nozzle in the direction of the central axis line.

The atmospheric plasma spraying method may be used in the forming of the film, and the position to which the slurry is supplied may be in the range from 0 mm to 30 mm from the tip end of the nozzle in the direction of the central axis line.

An angle between a central axis line of a slurry supplying nozzle configured to supply the slurry and the central axis line of the nozzle of the spraying gun may range from 45 degrees to 135 degrees at a side of the tip end of the nozzle of the spraying gun.

A temperature of the base may be set to be in a range from 100° C. to 300° C. in the forming of the film. The yttrium fluoride has a high thermal expansion coefficient. Thus, if the sprayed yttrium fluoride particles adhere to the surface of an underlying layer, those thermally sprayed particles may be rapidly cooled to be aggregated. As a result, the crack can occur in the film being formed. In accordance with the exemplary embodiment, since the temperature of the base is set to be in the range from 100° C. to 300° C., the crack in the film can be suppressed.

The manufacturing method may further include forming a first intermediate layer made of yttrium oxide between the base and the film. The first intermediate layer may be formed by the thermally spraying.

The manufacturing method may further include forming a mask on a region including an edge of the first intermediate layer. Here, the forming of the film is performed while the mask is formed on the region including the edge of the first intermediate layer in the forming of the mask. In accordance with the exemplary embodiment, it is possible to form the film only on the region of the first intermediate layer at the inner side than the edge of the first intermediate layer.

The manufacturing method may further include forming a second intermediate layer between the first intermediate layer and the film. The second intermediate layer may have a linear expansion coefficient that falls between a linear expansion coefficient of the first intermediate layer and a linear expansion coefficient of the film. By way of example, the second intermediate layer may be made of a thermally sprayed film of yttria-stabilized zirconia (YSZ), or a thermally sprayed film of forsterite. Alternatively, the second intermediate layer may be made of a thermally sprayed film of alumina or a thermally sprayed film of gray alumina. The second intermediate layer made of any of these materials can be formed by the thermally spraying.

The manufacturing method may further include forming another intermediate layer between the base and the first intermediate layer. Here, the another intermediate layer may be made of a thermally sprayed film of alumina or a thermally sprayed film of gray alumina. The another intermediate layer made of any of these materials can be formed by the thermally spraying.

The manufacturing method may further include forming an alumite film on the surface of the base.

According to the exemplary embodiments, it is possible to suppress generation of particles from the yttrium fluoride film.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

In the detailed description that follows, embodiments are described as illustrations only since various changes and modifications will become apparent to those skilled in the art from the following detailed description. The use of the same reference numbers in different figures indicates similar or identical items.

FIG. 1 is a diagram illustrating an example of a plasma processing apparatus;

FIG. 2 is an enlarged cross sectional view illustrating a part of a component for a plasma processing apparatus according to an exemplary embodiment;

FIG. 3 is an enlarged cross sectional view illustrating a part of a component for the plasma processing apparatus according to another exemplary embodiment;

FIG. 4A and FIG. 4B are enlarged cross sectional views illustrating a part of a component for the plasma processing apparatus according to still another exemplary embodiment;

FIG. 5 is a flowchart for describing a manufacturing method according to the exemplary embodiment;

FIG. 6A and FIG. 6B are diagrams illustrating a product produced in individual processes of the manufacturing method depicted in FIG. 5;

FIG. 7A to FIG. 7D are diagrams illustrating the product produced in individual processes of the manufacturing method depicted in FIG. 5;

FIG. 8 is a diagram for describing a high-velocity oxygen fuel spraying method according to the exemplary embodiment;

FIG. 9 is a diagram for describing an atmospheric plasma spraying method according to the exemplary embodiment;

FIG. 10 is a graph showing a breakdown voltage of a film;

FIG. 11 is a graph showing a breakdown voltage of a multilayered film; and

FIG. 12 is a graph showing a relationship between a processing time of a plasma process and the number of particles.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings, which form a part of the description. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. Furthermore, unless otherwise noted, the description of each successive drawing may reference features from one or more of the previous drawings to provide clearer context and a more substantive explanation of the current exemplary embodiment. Still, the exemplary embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein and illustrated in the drawings, may be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein.

First, an example plasma processing apparatus in which a component coated with a plasma-resistant film according to various exemplary embodiments will be explained. FIG. 1 illustrates an example of a plasma processing apparatus. The plasma processing apparatus 10 shown in FIG. 1 is configured as a capacitively coupled plasma etching apparatus, and includes a processing vessel 12. The processing vessel 12 has a substantially cylindrical shape. The processing vessel 12 is made of, but not limited to, aluminum, and an inner wall surface thereof is anodically oxidized. This processing vessel 12 is frame grounded.

A substantially cylindrical supporting member 14 is provided on a bottom portion of the processing vessel 12. The supporting member 14 is made of, by way of non-limiting example, an insulating material. Within the processing vessel 12, the supporting member 14 is vertically extended from the bottom portion of the processing vessel 12. Furthermore, a mounting table PD is provided within the processing vessel 12. The mounting table PD is supported by the supporting member 14.

The mounting table PD is configured to hold a wafer W on a top surface thereof. The mounting table PD has a lower electrode LE and an electrostatic chuck ESC. The lower electrode LE is provided with a first plate 18 a and a second plate 18 b. The first plate 18 a and the second plate 18 b are made of a metal such as, but not limited to, aluminum, and each thereof has a substantially disk shape. The second plate 18 b is provided on the first plate 18 a and electrically connected with the first plate 18 a.

The electrostatic chuck ESC is provided on the second plate 18 b. The electrostatic chuck ESC includes a pair of insulating films or insulating sheets; and an electrode embedded therebetween. The electrode of the electrostatic chuck ESC is made of a conductive film and is electrically connected to a DC power supply 22 via a switch 23. The electrostatic chuck ESC is configured to attract the wafer W by an electrostatic force such as a Coulomb force generated by a DC voltage applied from the DC power supply 22. Accordingly, the electrostatic chuck ESC is capable of holding the wafer W thereon.

A focus ring FR is provided on a peripheral portion of the second plate 18 b to surround an edge of the wafer W and the electrostatic chuck ESC. The focus ring FR is provided to improve etching uniformity. The focus ring FR is made of a material which is appropriately selected depending on a material of an etching target film. For example, the focus ring FR may be made of quartz.

A coolant path 24 is provided within the second plate 18 b. The coolant path 24 constitutes a temperature controller. A coolant is supplied into the coolant path 24 from a chiller unit provided outside of the processing vessel 12 via a pipeline 26 a. The coolant supplied into the coolant path 24 is then returned back into the chiller unit via a pipeline 26 b. In this way, the coolant is supplied into and circulated through the coolant path 24. A temperature of the wafer W held by the electrostatic chuck ESC is controlled by adjusting a temperature of the coolant.

Furthermore, the plasma processing apparatus 10 is provided with a gas supply line 28. The gas supply line 28 supplies a heat transfer gas, for example, a He gas, from a heat transfer gas supply device into a gap between a top surface of the electrostatic chuck ESC and a rear surface of the wafer W.

The plasma processing apparatus 10 is also equipped with a heater HT as a heating device. The heater HT is embedded within, for example, the second plate 18 b, and is connected to a heater power supply HP. As a power is supplied to the heater HT from the heater power supply HP, the temperature of the mounting table PD is adjusted, and, thus, the temperature of the wafer W placed on the mounting table PD can be adjusted. Alternatively, the heater HT may be embedded within the electrostatic chuck ESC.

Further, the plasma processing apparatus 10 includes an upper electrode 30. The upper electrode 30 is provided above the mounting table PD, facing the mounting table PD. The lower electrode LE and the upper electrode 30 are arranged to be substantially parallel to each other. Formed between the upper electrode 30 and the lower electrode LE is a processing space S in which a plasma process is performed on the wafer W.

The upper electrode 30 is supported on an upper portion of the processing vessel 12 via an insulating shield member 32. In the exemplary embodiment, the upper electrode 30 may be configured to have a variable distance in a vertical direction from a top surface of the mounting table PD, i.e., a wafer mounting surface. The upper electrode 30 may include an electrode plate 34 and an electrode supporting body 36. The electrode plate 34 faces the processing space S and is provided with a multiple number of gas discharge holes 34 a. The electrode plate 34 is an example of a component having plasma resistance.

The electrode supporting body 36 is configured to support the electrode plate 34 in a detachable manner, and is made of a conductive material such as, but not limited to, aluminum. The electrode supporting body 36 may have a water cooling structure. A gas diffusion space 36 a is formed within the electrode supporting body 36. A multiple number of gas through holes 36 b is extended downwards from the gas diffusion space 36 a, and these gas through holes 36 b respectively communicate with the gas discharge holes 34 a. Further, the electrode supporting body 36 is also provided with a gas inlet opening 36 c through which a processing gas is introduced into the gas diffusion space 36 a, and this gas inlet opening 36 c is connected to a gas supply line 38.

The gas supply line 38 is connected to a gas source group 40 via a valve group 42 and a flow rate controller group 44. The gas source group 40 includes a plurality of gas sources that supply different kinds of gases individually. The valve group 42 includes a multiplicity of valves, and the flow rate controller group 44 includes multiple flow rate controllers such as a mass flow controller. Each of the gas sources belonging to the gas source group 40 is connected to the gas supply line 38 via each corresponding valve belonging to the valve group 42 and each corresponding flow rate controller belonging to the flow rate controller group 44.

Furthermore, in the plasma processing apparatus 10, a deposition shield 46 is detachably provided along an inner wall of the processing vessel 12. The deposition shield 46 is also provided on an outer side surface of the supporting member 14. The deposition shield 46 is configured to suppress an etching byproduct (deposit) from adhering to the processing vessel 12, and is an example of components having plasma resistance.

A gas exhaust plate 48 is provided at a bottom portion of the processing vessel 12 and provided between the supporting member 14 and the inner wall of the processing vessel 12. The gas exhaust plate 48 may be made of, by way of example, but not limitation, an aluminum member coated with ceramic such as Y₂O₃. The processing vessel 12 is also provided with a gas exhaust opening 12 e under the gas exhaust plate 48, and the gas exhaust opening 12 e is connected with a gas exhaust device 50 via a gas exhaust line 52. The gas exhaust device 50 includes a vacuum pump such as a turbo molecular pump and is capable of depressurizing the inside of the processing vessel 12 to a desired vacuum level. Further, a carry-in/out opening 12 g for the wafer W is formed through a sidewall of the processing vessel 12, and this carry-in/out opening 12 g is opened or closed by a gate valve 54.

The plasma processing apparatus 10 further includes a first high frequency power supply 62 and a second high frequency power supply 64. The first high frequency power supply 62 is configured to generate a first high frequency power for plasma generation. That is, the first high frequency power supply 62 generates a high frequency power having a frequency in a range from 27 MHz to 100 MHz, e.g., 40 MHz. The first high frequency power supply 62 is connected to the lower electrode LE via a matching device 66. The matching device 66 is a circuit for matching an output impedance of the first high frequency power supply 62 and an input impedance on a load side (lower electrode LE). Furthermore, the first high frequency power supply 62 may be connected to the upper electrode 30 via the matching device 66.

The second high frequency power supply 64 is configured to generate a second high frequency power for ion attraction into the wafer W, i.e., a high frequency bias power having a frequency in a range from 400 kHz to 13.56 MHz, e.g., 3.2 MHz. The second high frequency power supply 64 is connected to the lower electrode LE via a matching device 68. The matching device 68 is a circuit for matching an output impedance of the second high frequency power supply 64 and the input impedance on the load side (lower electrode LE).

In the plasma processing apparatus 10 having the above-described configuration, a gas source selected from the plurality of gas sources belonging to the gas source group 40 supplies a gas into the processing vessel 12. Further, an internal space of the processing vessel 12 is depressurized to a preset pressure by the gas exhaust device 50, and plasma is generated within the processing vessel 12 by a high frequency electric field caused by applying the high frequency power from the first high frequency power supply 62. Here, the inner wall surfaces of the processing vessel 12, which form and confine the internal space thereof, are exposed to the generated plasma. For this reason, the deposition shield 46 and the electrode plate 34 are coated with a film having plasma resistance.

Below, various embodiments regarding a component having plasma resistance will be explained. FIG. 2 is an enlarged cross sectional view illustrating a part of a component for the plasma processing apparatus according to the exemplary embodiment. A component 100 shown in FIG. 2 can be used as, for example, the aforementioned deposition shield 46.

The component 100 has a base 102 and a film 104. The base 102 may be made of aluminum or an aluminum alloy. By way of example, the base 102 is a plate-shaped body made of A5052. Alternatively, the base 102 may be made of alumina (Al₂O₃), silicon carbide, silicon oxide, silicon, stainless steel, carbon or a combination thereof (for example, Si—SiC or alumina-silicon carbide).

In the exemplary embodiment, the base 102 may have an alumite film 106 formed on a main surface thereof. The alumite film 106 is formed by anodically oxidizing the base 102. In this exemplary embodiment, the alumite film 106 is formed only at a surface of a partial region of the base 102 including an edge thereof.

Further, in the exemplary embodiment, the main surface of the base 102 has a surface roughness equal to or smaller than a preset value. As will be described later, a film formed on the main surface of the base 102 has a surface roughness (arithmetic mean roughness: Ra) of 4.5 μm. Since the surface roughness of the film may reflect the surface roughness of the base 102, the surface roughness of the base 102 can be adjusted to a preset value or less. For example, the arithmetic mean roughness of the base 102 can be adjusted to 4.5 μm or less. Further, the arithmetic mean roughness (Ra) is defined by JIS B0601-1994.

The film 104 is formed on the base 102. The film 104 is made of yttrium fluoride and is formed by thermal spraying. The film 104 has a porosity ranging from 0.01% to 4%. In the film 104 having this porosity, a strong binding force between particles is obtained, so that particle generation from the film 104 can be suppressed. The porosity is defined as a value measured by a porosity measurement method to be described below.

[Porosity Measurement Method]

In this porosity measurement method, a field emission scanning electron microscope SU8200 produced by Hitachi High-Technology is used. As measurement conditions, an acceleration voltage of 1 kV, an emission current of 20 μA, and a work distance of 8 mm are set. A porosity is measured in the following sequence of (1) to (5).

-   -   (1) An initial sample having a film is cut.     -   (2) A cut surface is smoothed and cleaned by ion milling (refer         to the following description regarding the ion milling).     -   (3) The field emission scanning electron microscope is set to         have a magnification of 1000 times and focuses on the cut         surface.     -   (4) The field emission scanning electron microscope is set such         that obtained images have same brightness and same contrast         every time, and a back scattered electron image (BEI image) of         the cut surface is obtained.     -   (5) A binary image is obtained by binarizing the BEI image with         a threshold value of 175 from the image processing software (Win         Roof V50 produced by Mitani Corporation). A ratio of the area of         porous portions to the entire area of the cut surface within the         binary image is defined as a porosity.

[Ion Milling]

(1) Sample Cutting

A sample of a square of 1 cm is cut from the initial sample by a precision cutting machine.

(2) Resin Embedding

Epoxy resin is prepared, and a surface of the sample with the film thereon is submerged into the epoxy resin, and, then, the sample is subject to vacuum degassing.

(3) Polishing

The sample is polished by a water-resistant polishing paper (#1000) such that a distance between an observation target portion and a top surface of the sample is in a range from 100 μm to 500 μm.

The sample is polished by a water-resistant polishing paper (#1000) such that a distance between the observation target portion and a processed surface of the sample is about 50 μm.

A base portion of the sample is polished by a water-resistant polishing paper (#400) such that the base portion is parallel to the top surface of the sample.

(4) Ion Beam Irradiation

The sample is set in an ion beam irradiation device, and then, ion beams are irradiated to the observation target portion perpendicularly from the top surface of the sample, and the cut surface is processed.

(Conditions: an acceleration voltage of 6 [kV], a discharge voltage of 1.5 [kV], a gas flow rate of 0.07 [cm³/min] to 0.1 [cm³/min], and a processing time of 4 hours)

Further, the film 104 has a surface roughness of the arithmetic mean roughness (Ra) of 4.5 μm or less. The particle generation is suppressed from the film 104 having the surface roughness in this range.

In the exemplary embodiment, the film 104 may have a thickness ranging from 10 μm to 200 μm. With the film 104 having the thickness of 10 μm or more, even if the film 104 is consumed in a plasma environment, an underlying layer of the film 104 can be suppressed from being exposed. Further, with the film 104 having the thickness of 200 μm or less, adhesion between the film 104 and the underlying layer can be maintained.

In the exemplary embodiment, only the film 104, which is a single layer, may be directly formed on the base 102. In another exemplary embodiment, a multilayered film ML including the film 104 may be formed on the base 102, as illustrated in FIG. 2, for example.

In the another exemplary embodiment depicted in FIG. 2, the multilayered film ML further includes an intermediate layer 108 in addition to the film 104. The intermediate layer 108 is made of yttrium oxide and is formed by the thermal spraying such as atmospheric plasma spraying. In the exemplary embodiment, the intermediate layer 108 is formed on a clean surface of the base 102 and on a partial region of the alumite film 106 which is continuous with the clean surface. That is, the intermediate layer 108 is not formed on a region of the base 102 including the edge thereof.

Here, an adhesive strength of the yttrium fluoride film to the base 102 is 8.8 MPa, and an adhesive strength of the yttrium oxide film to the base 102 is 12.8 MPa. Accordingly, by providing the intermediate layer 108 between the base 102 and the film 104, the adhesive strength of the multilayered film ML to the base 102 can be improved. Further, the intermediate layer 108 may have a porosity in the range from, for example, 3% to 10%. Furthermore, the intermediate layer 108 may have a thickness in the range from 10 μm to 200 μm. With the intermediate layer 108 in such a thickness range, the above-stated adhesive strength can be maintained.

Moreover, the yttrium fluoride, which forms the film 104, has a relatively low breakdown voltage. Meanwhile, the yttrium oxide, which forms the intermediate layer 108, has a relatively high breakdown voltage. By providing this intermediate layer 108 between the film 104 and the base 102, a breakdown voltage of the multilayered film ML including the intermediate layer 108 and the film 104 can be increased.

Furthermore, in the exemplary embodiment, the thicknesses of the film 104 and the intermediate layer 108 may be equal to or larger than 100 μm. With the multilayered film ML having the film 104 and the intermediate layer 108 in such a thickness range, it is possible to obtain a high breakdown voltage even in a high temperature environment.

In the exemplary embodiment, the film 104 is not formed on a region R1 including an edge of the intermediate layer 108, but is formed on an inner region R2 than the region R1. On the region R1 including the edge thereof, cracks of the film may be easily created during the thermal spraying process. In view of this, the film 104 is not formed on the region R1, and, thus, cracks of the film 104 can be suppressed.

FIG. 3 is an enlarged cross sectional view illustrating a part of a component for the plasma processing apparatus according to another exemplary embodiment. A component 100A depicted in FIG. 3 may be used as the aforementioned electrode plate 34, for example. Thus, a base 102 of the component 100A shown in FIG. 3 is provided with a hole HL corresponding to a gas discharge hole 34 a. The hole HL has a taper shape with a width increasing from the vicinity of an opening end thereof toward the opening end.

At the base 102 of the component 100A, an alumite film 106 is formed on a surface portion which forms the hole HL and a partial region which is continuous with this surface portion. Further, in this component 100A, an intermediate layer 108 is formed on a clean surface of the base 102 and on the alumite film 106. Further, in the component 100A, the intermediate layer 108 is extended to the inside of the hole HL. The film 104 is not formed in the vicinity of the hole HL, i.e., on a region R1 including an edge of the intermediate layer 108, but is formed on a flat region R2 of the intermediate film 108. At the region R1 of the component 100A, there may easily occur cracks of the film during a thermal spraying process. Thus, the film is not formed on the region R1, and, thus, a damage of the film 104 can be suppressed.

Now, referring to FIG. 4A and FIG. 4B, a component according to still another exemplary embodiment will be explained. FIG. 4A and FIG. 4B are enlarged cross sectional views illustrating a part of a component for the plasma processing apparatus according to still another exemplary embodiment. In a component 100B depicted in FIG. 4A, a multilayered film ML further includes an intermediate layer 110. The intermediate layer 110 is provided between a film 104 and an intermediate layer 108. The intermediate layer 110 may be formed by the thermal spraying. The intermediate layer 110 may have a thickness in the range from, by way of example, but not limitation, 10 μm to 500 μm to achieve sufficient adhesivity.

As one example, the intermediate layer 110 is made of yttria-stabilized zirconia (YSZ), or forsterite. The intermediate layer 110 may be formed by the atmospheric plasma spraying method. Here, a linear expansion coefficient of the film 104 is about 14×10⁻⁶K⁻¹, and a linear expansion coefficient of the intermediate layer 108 is about 7.3×10⁻⁶K⁻¹. Further, a linear expansion coefficient of the YSZ is 9×10⁻⁶K⁻¹, and a linear expansion coefficient of the forsterite is 10×10⁻⁶K⁻¹. That is, the intermediate layer 110 made of the YSZ or the forsterite has a linear expansion coefficient that falls between the linear expansion coefficient of the film 104 and the linear expansion coefficient of the intermediate layer 108. Thus, by providing this intermediate layer 110 between the film 104 and the intermediate layer 108, peeling of the film 104 that might be caused by a difference in the linear expansion coefficients between the film 104 and the intermediate layer 108 can be suppressed.

As another example, the intermediate layer 110 may be made of a thermally sprayed alumina film or a thermally sprayed gray alumina (alumina—about 2.5% of titania) film. By using this intermediate layer 110, the multilayered film ML including the film 104, the intermediate layer 108 and the intermediate layer 110 and having a high breakdown voltage is provided on the base 102.

In a component 100C depicted in FIG. 4B, a multilayered film ML may further include an intermediate layer 112. The intermediate layer 112 is provided between a base 102 and an intermediate layer 108. The intermediate layer 112 may have a thickness in the range from, by way of non-limiting example, 10 μm to 500 μm in order to improve the adhesivity thereof. The intermediate layer 112 may be made of a thermally sprayed alumina film or a gray alumina (alumina—about 2.5% of titania). This intermediate layer 112 may be formed by the atmospheric plasma spraying method. By using this intermediate layer 112, the multilayered film ML including a film 104, the intermediate layer 108 and the intermediate layer 112 and having a high breakdown voltage is provided on the base 102.

Now, a manufacturing method of manufacturing the component according to the above-described various embodiments will be explained. FIG. 5 is a flowchart for describing a manufacturing method according to the exemplary embodiment. FIG. 6A to FIG. 7D are diagrams illustrating a product in individual processes of the manufacturing method of FIG. 5.

The manufacturing method PM described in FIG. 5 starts from a process S1 (perform alumite-treatment on base). At the process S1, an alumite-treatment (anodic oxidation) of a base 102 is performed. At the process S1, as depicted in FIG. 6A, a mask MK1 is prepared on the base 102. The mask MK1 is provided on the base 102 to allow only a region of the base 102 on which the alumite-treatment will be performed to be exposed. Then, the alumite-treatment is performed, so that an alumite film 106 is formed, as illustrated in FIG. 6B.

Subsequently, a process S2 (perform surface conditioning on base) is performed, as depicted in FIG. 5. At the process S2, a surface conditioning is performed on a surface of the base 102. For the process S2, a surface conditioning using a diamond whetstone, a SiC whetstone, a diamond film, or the like, or a buffing surface conditioning may be performed. Alternatively, for the surface conditioning of the process S2, a CO₂ blasting or a blasting with alumina or SiC may be performed. At the process S2, the surface of the base 102 is surface-controlled such that the surface roughness (arithmetic mean roughness (Ra)) is 4.5 μm or less in a case of providing the single layer, and 5.5 μm or less in a case of providing the intermediate layer.

In a subsequent process S3 (form intermediate layer), an intermediate layer is formed. When producing the component 100 and the component 100A, the intermediate layer 108 is formed. When producing the component 100B, the intermediate layer 108 and the intermediate layer 110 are formed. When forming the component 100C, the intermediate layer 112 and the intermediate layer 108 are formed. When forming each intermediate layer in the process S3, the thermal spraying is performed by using a slurry that contains particles of a material forming each intermediate layer. For this thermal spraying, various thermal spraying methods such as an atmospheric plasma spraying (APS) method and a high velocity oxygen fuel (HVOF) spraying method may be used. Furthermore, when forming the intermediate layer 108, the slurry containing particles having a diameter ranging from 10 μm to 35 μm may be used. The slurry containing the particles of this particle size can be prepared at a low cost.

FIG. 7A and FIG. 7B depict a product produced in the course of forming the intermediate layer 108 of the component 100. In the exemplary embodiment, as illustrated in FIG. 7A, a mask MK2, which allows only a region where an intermediate layer is to be formed to be exposed, is formed on the base 102. Then, an intermediate layer is formed by the thermal spraying. By way of example, as illustrated in FIG. 7B, the intermediate layer 108 is formed by the thermal spraying.

In a subsequent process S4 (perform surface conditioning on underlying layer), a surface conditioning is performed on the underlying layer, which is the topmost intermediate layer. For this process S4, a surface conditioning using a diamond whetstone, a SiC whetstone, a diamond film, or the like, or a buffing surface conditioning may be performed. Alternatively, for the surface conditioning of the process S4, a CO₂ blasting or a blasting with alumina or SiC may be performed. In this process S4, the surface of the base 102 is surface-controlled such that the surface roughness (arithmetic mean roughness (Ra)) is 4.5 μm or less. Furthermore, when forming the film 104 directly on the base 102, the process S3 and the process S4 may not be performed.

In a subsequent process S5 (form film), the film 104 is formed. At the process S5, as illustrated in FIG. 7C, a mask MK3, which allows an underlying region (for example, a region R2) on which the film 104 is to be formed to be exposed, is formed. Then, the film 104 is formed, as depicted in FIG. 7D, by the thermal spraying with a slurry containing yttrium fluoride particles.

FIG. 8 is a diagram for describing a high velocity oxygen fuel spraying method according to the exemplary embodiment. FIG. 9 is a diagram for describing an atmospheric plasma spraying method according to the exemplary embodiment. For the thermal spraying in the process S5, the high velocity oxygen fuel (HVOF) spraying method depicted in FIG. 8 or the atmospheric plasma spraying (APS) method depicted in FIG. 9 may be performed.

As shown in FIG. 8, a spraying apparatus SA1 for the HVOF method of forming the film 104 is equipped with a spraying gun SG1 and a slurry supplying nozzle SN. The spraying gun SG1 includes a combustion vessel unit BC forming a combustion chamber BS; a nozzle NG1 adjacent to the combustion vessel unit BC; and an ignition device ID. In the spraying gun SG1, a gas, which contains high-pressure oxygen and a fuel, is supplied into the combustion chamber BS, and the ignition device ID ignites the gas. Flame (combustion flame) generated in the combustion chamber BS is collected in the nozzle NG1 and jetted from the nozzle NG1. The slurry is supplied from the nozzle SN into the jetted flame. Accordingly, the particles in the slurry are melted or semi-melted, and then, sprayed, in a melted or semi-meted state, onto a product WP on which the film 104 is to be formed.

When forming the film 104 by the HVOF method, the slurry is supplied to a position distanced apart from a tip end of the nozzle NG1 or a position corresponding to the tip end of the nozzle NG1 in a direction of a central axis line AX1 of the nozzle NG1 of the spraying gun SG1, as shown in FIG. 8. That is, a distance X from the tip end of the nozzle NG1 to the slurry supply position is set to be 0 mm or larger.

As depicted in FIG. 9, a spraying apparatus SA2 for the APS method of forming the film 104 is equipped with a spraying gun SG2 and a nozzle SN configured to supply a slurry. The spraying gun SG2 includes a vessel unit PC forming a plasma generation space PS; a nozzle NG2 adjacent to the vessel unit PC; and an electrode ET. The vessel unit PC is made of an insulator, and the nozzle NG2 is made of a conductor. The electrode ET is provided within the vessel unit PC. In this spraying gun SG2, an operation gas is supplied into the vessel unit PC, and a voltage is applied between the electrode ET and the nozzle NG2. Accordingly, plasma of the operation gas is generated to be jetted from the nozzle NG2. Then, the slurry is supplied from the nozzle NG2 into the jetted plasma, so that particles in the slurry are melted or semi-melted and then, sprayed, in a melted or semi-melted state, onto a product WP on which the film 104 is to be formed.

When forming the film 104 by the APS method, as depicted in FIG. 9, the slurry is supplied to a position distanced apart from a tip end of the nozzle NG2 or a position corresponding to the tip end of the nozzle NG2 in a direction of a central axis line AX1 of the nozzle NG2 of the spraying gun SG1. That is, a distance X from the tip end of the nozzle NG2 to the slurry supply position is set to be 0 mm or larger.

In the process S5 using any of the HVOF method and the APS method, the slurry may contain yttrium fluoride particles, a dispersion medium and an organic dispersant. The dispersion medium is water or alcohol. The yttrium fluoride particles are contained in this slurry at a mass ratio of 5% to 40%. A diameter of each yttrium fluoride particle is in the range from 1 μm to 8 μm. Further, an average particle diameter is defined as a diameter measured by laser diffraction/scattering method (micro-track method).

The film 104 is formed by the above-described thermal spraying method. Subsequently, if the mask MK2 and the mask MK3 are removed, the component is obtained, and the manufacturing method PM is finished.

In this manufacturing method PM, since the film 104 is formed on the surface of the underlying layer which has undergone through the surface conditioning on which the surface conditioning has been performed, the surface roughness of the film 104 is reduced. This film 104 has a small specific surface area, so that the particle generation from the film 104 can be suppressed. Furthermore, since the average diameter of the particles contained in the slurry ranges from 1 μm to 8 μm, aggregation of the particles is suppressed, so that the film 104 can be made uniform. Moreover, since the average diameter of the particles contained in the slurry is in the range from 1 μm to 8 μm, it is possible to form the film having high adhesivity between the particles. In addition, since the slurry is supplied onto the aforementioned position, it is possible to suppress the sprayed material from adhering to the inner wall of the nozzle of the spraying gun or the like. As a result, a spitting can be suppressed. Thus, according to this manufacturing method PM, a film having a low porosity and a small specific surface area, i.e., a highly dense film 104 can be formed. In this film 104, a little change in the surface thereof occurs even when it is exposed to the plasma, and, thus, a variation in process performance can be reduced. Therefore, according to this manufacturing method PM, it is possible to form a film capable of suppressing the particle generation.

When performing the HVOF method in the process S5 of the exemplary embodiment, the position to which the slurry is supplied is in the range from 0 mm to 100 mm in the direction of the central axis line AX1 from the tip end of the nozzle NG1 of the spraying gun SG1. That is, the distance X depicted in FIG. 8 ranges from 0 mm to 100 mm. Further, when performing the APS method in the process S5, the position to which the slurry is supplied is in the range from 0 mm to 30 mm in the direction of the central axis line AX1 from the tip end of the nozzle NG2 of the spraying gun SG2. That is, the distance X shown in FIG. 9 ranges from 0 mm to 30 mm.

Furthermore, whichever one of the HVOF method and the APS method is selected as the spraying method in the process S5, an angle θ shown in FIG. 8 and FIG. 9 is zero (0) degree, or in the range from 45 degrees to 135 degrees. The angle θ is formed between the central axis line AX2 of the nozzle SN and the central axis line AX1 at the side of the tip end of the nozzle of the spraying gun.

In addition, in the process S5 in the exemplary embodiment, the product WP including the base 102 is set to have a temperature ranging from 100° C. to 300° C. during the thermal spraying process. The yttrium fluoride has a high thermal expansion coefficient. Thus, if the sprayed yttrium fluoride particles adhere to the surface of the underlying layer, those thermally sprayed particles may be rapidly cooled and aggregated, so that the cracks can occur in the film being formed. According to the exemplary embodiment, however, since the temperature of the product WP including the base 102 is set to be in the range from 100° C. to 300° C., it is possible to suppress the cracks in the film 104.

Further, in case of performing the HVOF method in the process S5, an oxygen/fuel ratio is set to be a value higher than a theoretical oxygen/fuel ratio required for the complete combustion of the fuel. Accordingly, generation of soot caused by the incomplete combustion can be suppressed, and introduction of the soot into the film 104 can be suppressed.

In the above, the various exemplary embodiments have been described. However, the exemplary embodiments are not limiting, and various changes and modifications may be made. By way of example, the plasma processing apparatus with the above-described plasma-resistant components may not be limited to the capacitively coupled plasma processing apparatus. The plasma-resistant components may be applied to various types of plasma processing apparatus such as an inductively coupled plasma processing apparatus, a plasma processing apparatus that generates plasma by a microwave, and so forth.

Below, experiments conducted to evaluate the manufacturing method PM and the film 104 will be described.

<Evaluation of X and θ in Thermal Spraying in Process S5 of Manufacturing Method PM>

Thermally sprayed yttrium fluoride films are prepared by performing the HVOF method and the APS method, respectively, while varying X and θ depicted in FIG. 8 and FIG. 9 in various ways. To form the thermally sprayed films, the slurry containing yttrium fluoride particles having an average diameter of 1.5 μm and a mass ratio of 35% is used. Further, in the thermal spraying process, the temperature of the target object, i.e., the temperature of the product including the base is set to 250° C.

Then, the produced thermally sprayed films are evaluated based on evaluation items to be described below. In the description of the evaluation items, the term “after the plasma process” means a time point after the thermally sprayed film formed on the sample is exposed to the plasma for 10 hours. Here, the plasma is generated by placing the sample on which the thermally sprayed film has been formed in the plasma processing apparatus 10; by supplying a gas containing CF₄, Ar and O₂ into the processing vessel 12; and by setting the high frequency power from the first high frequency power supply 62 to 1500 W.

<Evaluation Items>

(Consumption)

A level difference between a masked region and a non-masked region of the thermally sprayed film on the sample after the plasma process is measured by a profiler. If the level difference equivalent to or larger than the thickness of the thermally sprayed film is observed, it is determined that the thermally sprayed film has been consumed.

(Split/Crack)

When observing the appearance of the thermally sprayed film with naked eyes, if a stripe-shaped or a mesh-shaped crack is clearly found in the thermally sprayed film, it is evaluated as “split presence” or “crack presence.” Furthermore, When observing the cross section of the thermally sprayed film with the SEM, if there is found a crack that passes through the thermally sprayed film in the thickness direction thereof, or a continuous crack having a length of 30 μm or longer, it is also evaluated as “split presence” or “crack presence.”

(Peeling)

When observing the appearance of the thermally sprayed film with naked eyes, if the thermally sprayed film is found to be peeled off apparently, or if a minute gap between the thermally sprayed film and the underlying layer is found, it is determined that the thermally sprayed film is peeled off. Further, when observing the cross section of the thermally sprayed film with the SEM, if a continuous minute gap having a length of 50 μm or larger between the thermally sprayed film and the underlying layer is found, it is also evaluated that the thermally sprayed film is peeled off.

(Adhesion Ratio)

A ratio of a weight of the thermally sprayed film to a weight of the used particles is calculated, and when this ratio is equal to or less than 1%, it is evaluated as “Low adhesion ratio.”

(Material Adhesion to Nozzle of Spraying Gun)

When observing an inner wall of the nozzle of the spraying gun and an appearance in the vicinity of an outlet of the nozzle with naked eyes, if there are observed melted particles adhering to the spraying gun, it is determined that the particles are melt to adhere thereto.

(Particle Evaluation)

A carbon tape is placed on the thermally sprayed film after the plasma process, and a 26 g-weight made of polytetrafluoroethylene is mounted on the carbon tape. Thereafter, the weight is removed and the carbon tape is detached. Then, the carbon tape is observed by the SEM. Further, a ratio of the area of a transcribed region to the entire area of the carbon tape on the SEM image is calculated, and this ratio is defined as a transcription ratio. If the transcription ratio of the thermally sprayed film as the evaluation target is larger than a transcription ratio of a thermally sprayed film created by the APS method with the slurry containing yttrium fluoride particles having an average diameter of 50 μm while setting X=5 mm and θ=90 degrees, it is concluded that the thermally sprayed film as the evaluation target has “Particle defect.”

Table 1 shows values of X and θ, and evaluation results for the thermally sprayed film that is produced. As for the evaluation results, “Good” implies that the thermally sprayed film exhibits favorable characteristics for all of the above-described evaluation items.

TABLE 1 Thermal Spraying Method X (mm) θ (degree) Evaluation Result HVOF 130 90 Particle defect 100 45 Good 100 90 Good 100 135 Good 50 90 Good 0 45 Good 0 90 Good 0 135 Good −30 90 Melt particles adhesion to the inner wall of the nozzle 50 30 Low adhesion ratio 50 45 Good 50 135 Good 50 150 Melt particles adhesion to the vicinity of nozzle outlet 0 0 Good −30 0 Melt particles adhesion to the inner wall of the nozzle APS 40 90 Particle defect 30 135 Good 30 90 Good 30 45 Good 15 90 Good 0 135 Good 0 90 Good 0 45 Good −20 90 Melt particles adhesion to the inner wall of the nozzle 15 30 Low adhesion ratio 15 45 Good 15 135 Good 15 150 Melt particles adhesion to the vicinity of nozzle outlet 0 0 Good −30 0 Melt particles adhesion to the inner wall of the nozzle

As shown in Table 1, in the HVOF method, the “Particle defect” is found when X is 130 mm. Further, in the HVOF method, when X has a negative value, it is found that the particles are melted to adhere to the inner wall of the nozzle of the spraying gun. In addition, in the HVOF method, it is found that a favorable thermally sprayed film can be formed when X is in the range from 0 mm to 100 mm. Furthermore, in the HVOF method, when θ is 30 degrees, the “Low adhesion ratio” is found, and when θ is 150 degrees, melted particles are found to adhere to the vicinity of the nozzle outlet of the spraying gun. Furthermore, when θ is in the range from 45 degrees to 135 degrees, it is proved that a favorable thermally sprayed film can be formed.

Further, in the APS method, the “Particle defect” is found when X is 40 mm. When X has a negative value, it is found that the particles are melted to adhere to the inner wall of the nozzle of the spraying gun. In addition, it is found that a favorable thermally sprayed film can be formed when X is in the range from 0 mm to 30 mm. Furthermore, in the APS method, when θ is 30 degrees, the “Low adhesion ratio” is found, and when θ is 150 degrees, melt particles are found to adhere to the vicinity of the nozzle outlet of the spraying gun. Furthermore, when θ is in the range from 45 degrees to 135 degrees, it is found that a favorable thermally sprayed film can be formed.

<Evaluation Regarding Temperature of Base During Thermal Spraying of Process S5 in Manufacturing Method PM>

Thermally sprayed yttrium fluoride films are prepared by performing the HVOF method and the APS method, respectively, while varying the temperature of the product including the base in various ways. To form the thermally sprayed film, the slurry containing yttrium fluoride particles having an average diameter of 1.5 μm and a mass ratio of 35% is used. Further, in the HVOF method, X and θ are set to be X=50 mm and θ=90 degrees. In the APS method, X and θ are set to be X=15 mm and θ=90 degrees. Then, the produced thermally sprayed films are evaluated in view of the crack, which is one of the aforementioned evaluation items, and, also, in view of base deformation. Table 2 provides evaluation results.

TABLE 2 Temperature of Base (° C.) Evaluation Result 350 No crack but large base deformation 300 No crack, no base deformation 250 No crack, no base deformation 100 No crack, no base deformation 48 Crack presence

As can be seen from Table 2, when the temperature of the product including the base is 48° C., the crack is generated in the thermally sprayed film, and when the temperature is 350° C., a relatively large base deformation is generated. Further, when the temperature is in the range form 100° C. to 300° C., neither the crack nor the base deformation are generated. This result proves that if the temperature of the base is set to be in the range from 100° C. to 300° C., the crack in the thermally sprayed film and the base deformation can be both suppressed.

<Evaluation Regarding Diameter of Particle During Slurry During Thermal Spraying in Process S5 in the Manufacturing Method PM>

Thermally sprayed yttrium fluoride films are prepared by performing the HVOF method and the APS method, respectively, while varying an average diameter of yttrium fluoride particles in various ways. To form the thermally sprayed film, the slurry containing yttrium fluoride particles at a mass ratio of 35% is used. Further, in the HVOF method, X and θ are set to be X=50 mm and θ=90 degrees. In the APS method, X and θ are set to be X=15 mm and θ=90 degrees. Further, the temperature of the product including the base is set to 250° C. Then, the produced thermally sprayed films are evaluated based on the aforementioned evaluation items. Also, the porosity and the thickness of each of the produced thermally sprayed films are calculated. Table 3 provides evaluation results.

TABLE 3 Average Particle Film Diameter (μm) Porosity (%) Thickness (μm) Evaluation Result 15 4.4 130 Particle defect 8 4 130 Good 4.2 2.5 120 Good 1.5 1.8 130 Good 1 0.2 130 Good 0.82 1.5 120 Crack presence 1.5 1.8 250 Peeled 1.5 1.8 200 Good 1.5 1.8 10 Good 1.5 1.8 5 Consumed

As can be seen from Table 3, when the average diameter of the particles in the slurry is 15 μm, the “Particle defect” is found, and when the average diameter of the particles is 0.82 μm, the crack in the thermally sprayed film is found. Further, when the average diameter of the particles is in the range from 1 μm to 8 μm, favorable thermally sprayed films are formed. In view of this, it is found that if the average diameter of the particles in the slurry is in the range from 1 μm to 8 μm, a favorable thermally sprayed film can be formed. Furthermore, when the porosity of the thermally sprayed film is 4.4%, the “Particle defect” is found, and when the porosity is 4% or less, no particle defect is found. In view of this, it is found that if the porosity is 4% or less, the particle generation can be suppressed. In addition, when the thickness of the thermally sprayed film is 5 μm, it is found that the consumption of the thermally sprayed film after the plasma process is large. Moreover, the peeling of the thermally sprayed film is found when its thickness is 250 μm. From this, it is also found that if the thickness of the thermally sprayed film is in the range from 10 μm to 200 μm, the thermally sprayed film can be maintained even if it is consumed by the plasma process, and, also, the peeling of the thermally sprayed film can be suppressed.

<Evaluation Regarding Surface Roughness>

Thermally sprayed yttrium fluoride films having different surface roughness are prepared while adjusting surface roughness of the base. The HVOF method is performed as the thermal spraying. Further, the slurry containing yttrium fluoride particles having an average diameter of 1.5 μm and a mass ratio of 35% is used in the thermal spraying. In the HVOF method, X and θ are set to be X=50 mm and θ=90 degrees. Then, among the aforementioned evaluation items, the particle evaluation is made. When Ra is 4.8 μm, it is determined that there is “Particle defect”, and when Ra is 4.5 μm and 3.5 μm, respectively, no particle defect is observed. In view of this result, it is found that if the thermally sprayed film has the surface roughness of Ra=4.5 μm or less, the particle generation therefrom can be suppressed.

<Evaluation Regarding Breakdown Voltage>

Single-layered films made of yttrium fluoride are formed on the base while varying thicknesses of the films in various ways. Furthermore, a multilayered film, which includes an intermediate layer of yttrium oxide having a thickness of 100 μm and an yttrium fluoride film having a thickness of 100 μm, is formed on the base. Then, the breakdown voltages of the single-layered films and the multilayered film are measured while varying the temperature. FIG. 10 shows the breakdown voltages of the single-layered films. In FIG. 10, a vertical axis represents the breakdown voltage, and upper-side values presented along a horizontal axis indicate the thickness μm of the single-layered films and lower-side values presented along the horizontal axis represent the temperature (° C.) of the films when the breakdown voltage is measured. Further, ‘RT’ represents the room temperature. Moreover, FIG. 11 presents the breakdown voltage of the multilayered films. In FIG. 11, a vertical axis represents the breakdown voltage, and values presented along a horizontal axis indicate the temperature (° C.) of the multilayered film when the breakdown voltage is measured.

As can be seen from FIG. 10, the yttrium fluoride single-layered films show higher breakdown voltages as they have larger thicknesses. In the high temperature environment, however, the breakdown voltage is found to be decreased. As can be seen from FIG. 11, it is found that by providing the intermediate layer made of yttrium oxide having the thickness of 100 μm between the film and the base, it is possible to suppress the breakdown voltage of the multilayered film from being reduced even in the high temperature environment.

<Evaluation Regarding Number of Particles Generated by Plasma Process in Plasma Processing Apparatus Equipped with Electrode Plate 34 Having Film and Intermediate Layer>

There is prepared an electrode plate 34 (refer to the component 100A of FIG. 3) including an intermediate layer, which is made of yttrium oxide and has a thickness of 150 μm, formed on an aluminum base; and a film, which is made of yttrium fluoride and has a thickness of 50 μm, a surface roughness (arithmetic mean roughness (Ra)) of 1.43 μm and a porosity of 2.39% (hereinafter, referred to as “Film 1”), formed on the intermediate layer. Further, a plasma processing apparatus 10 is provided with the electrode plate 34 (hereinafter, referred to as “plasma processing apparatus 10 having Film 1”). A wafer is mounted on the mounting table PD of the plasma processing apparatus 10, and the plasma process is performed. In the plasma process, a gaseous mixture containing a C₄F₈ gas, a C₄F₆ gas, a CF₄ gas, an Ar gas, an O₂ gas, and a CH₄ gas is supplied into the processing vessel 12 at a total flow rate of 425 sccm, and a total power of the high frequency power from the first high frequency power supply 62 and the high frequency power from the second high frequency power supply 64 is set to be 5000 W. Then, a relationship between a processing time of the plasma process and the number of particles generated on the wafer is obtained. Further, in the measurement of the particles, the number of particles having a size of 45 nm or larger is measured by using Surfscan SP2 produced by KLA-Tencor.

Further, there is also prepared an electrode plate 34 (refer to the component 100A of FIG. 3) including an intermediate layer, which is made of yttrium oxide and has a thickness of 150 μm, formed on an aluminum base; and a film, which is made of yttrium fluoride and has a thickness of 50 μm, a surface roughness (arithmetic mean roughness (Ra)) of 5.48 μm and a porosity of 5.21% (hereinafter, referred to as “Film 2”), formed on the intermediate layer. Further, a plasma processing apparatus 10 is provided with the rode plate 34 (hereinafter, referred to as “plasma processing apparatus 10 having Film 2”). A wafer is mounted on the mounting table PD of the plasma processing apparatus 10, and the same plasma process as that performed in case of using the plasma processing having Film 1 is performed. Then, as in the case of using the plasma processing apparatus 10 having Film 1, a relationship between a processing time of the plasma process and the number of particles generated on the wafer is obtained.

FIG. 12 is a graph showing a relationship between the processing time of the plasma process and the number of the particles. In FIG. 12, a horizontal axis represents the processing time h of the plasma process, and a vertical axis indicates the number of particles. Further, a solid line on the graph indicates a regression line of the number of the particles generated at each of a plurality of processing times when using the plasma processing apparatus 10 having Film 1, and a dashed line on the graph indicates a regression line of the number of the particles generated at each of multiple processing times when using the plasma processing apparatus 10 having Film 2. As shown in FIG. 12, the number of the particles generated by the plasma process in the plasma processing apparatus 10 having Film 1 is found to be considerably reduced, as compared to the number of the particles generated by the plasma process in the plasma processing apparatus 10 having Film 2. That is, it is found that the particle generation by the plasma process can be suppressed, according to the plasma processing apparatus including the electrode plate 34 provided with the film having the porosity of 4% or less and the surface roughness (arithmetic mean roughness (Ra)) of 4.5 μm or less.

From the foregoing, it will be appreciated that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting. 

We claim:
 1. A component for a plasma processing apparatus, comprising: a base; and a film formed by thermally spraying yttrium fluoride onto a surface of the base or on a surface of an underlying layer including a layer provided on the base, wherein a porosity of the film is 4% or less, and an arithmetic mean roughness of a surface of the film is 4.5 μm or less.
 2. The component of claim 1, further comprising: a first intermediate layer which is made of an yttrium oxide film formed by an atmospheric plasma spraying method, and is provided between the base and the film.
 3. The component of claim 2, wherein the film is not formed on a region including an edge of the first intermediate layer, but is formed on the first intermediate layer at an inner side than the region.
 4. The component of claim 2, further comprising: a second intermediate layer provided between the first intermediate layer and the film.
 5. The component of claim 4, wherein the second intermediate layer has a linear expansion coefficient that falls between linear expansion coefficients of the first intermediate layer and the film.
 6. The component of claim 5, wherein the second intermediate layer is formed of a thermally sprayed film of forsterite or a thermally sprayed film of yttria-stabilized zirconia (YSZ) formed by the atmospheric plasma spraying method.
 7. The component of claim 5, wherein the second intermediate layer is made of a thermally sprayed film of gray alumina or a thermally sprayed film of alumina formed by the atmospheric plasma spraying method.
 8. The component of claim 2, further comprising: another intermediate layer provided between the base and the first intermediate layer.
 9. The component of claim 8, wherein the another intermediate layer is formed of a thermally sprayed film of gray alumina or a thermally sprayed film of alumina formed by the atmospheric plasma spraying method.
 10. The component of claims 1, wherein an alumite film is formed on the surface of the base.
 11. The component of claims 1, wherein the base is made of aluminum or an aluminum alloy.
 12. A manufacturing method for a component in a plasma processing apparatus, the manufacturing method comprising: performing a surface conditioning on a surface of an underlying layer on which a film is to be formed by thermal spraying, the surface of the underlying layer includes a surface of a base or a surface of a layer formed on the surface of the base; and forming the film on the surface of the underlying layer by thermally spraying yttrium fluoride, wherein, in the forming of the film, a slurry containing yttrium fluoride particles having an average diameter ranging from 1 μm to 8 μm is supplied, from a nozzle of a spraying gun configured to jet a flame in a high velocity oxygen fuel spraying method or from a nozzle of a spraying gun configured to discharge a plasma jet in an atmospheric plasma spraying method, to a position distanced apart from the nozzle of the spraying gun toward a downstream side in a direction of a central axis line of the nozzle of the spraying gun or to a position corresponding to a tip end of the nozzle of the spraying gun.
 13. The manufacturing method of claim 12, wherein the high velocity oxygen fuel spraying method is used in the forming of the film, and the position to which the slurry is supplied is in the range from 0 mm to 100 mm from the tip end of the nozzle in the direction of the central axis line.
 14. The manufacturing method of claim 12, wherein the atmospheric plasma spraying method is used in the forming of the film, and the position to which the slurry is supplied is in the range from 0 mm to 30 mm from the tip end of the nozzle in the direction of the central axis line.
 15. The manufacturing method of claims 12, wherein an angle between a central axis line of a slurry supplying nozzle configured to supply the slurry and the central axis line of the nozzle of the spraying gun ranges from 45 degrees to 135 degrees at a side of the tip end of the nozzle of the spraying gun.
 16. The manufacturing method of claim 12, wherein a temperature of the base is set to be in a range from 100° C. to 300° C. in the forming of the film.
 17. The manufacturing method of claims 12, further comprising: forming a first intermediate layer made of yttrium oxide between the base and the film.
 18. The manufacturing method of claim 17, further comprising: forming a mask on a region including an edge of the first intermediate layer, wherein the forming of the film is performed while the mask is formed on the region including the edge of the first intermediate layer in the forming of the mask.
 19. The manufacturing method of claim 17, further comprising: forming a second intermediate layer between the first intermediate layer and the film.
 20. The manufacturing method of claim 19, wherein the second intermediate layer has a linear expansion coefficient that falls between a linear expansion coefficient of the first intermediate layer and a linear expansion coefficient of the film.
 21. The manufacturing method of claim 20, wherein the second intermediate layer is made of a thermally sprayed film of yttria-stabilized zirconia (YSZ), or a thermally sprayed film of forsterite.
 22. The manufacturing method of claim 19, wherein the second intermediate layer is made of a thermally sprayed film of alumina or a thermally sprayed film of gray alumina.
 23. The manufacturing method of claim 17, further comprising: forming another intermediate layer between the base and the first intermediate layer.
 24. The manufacturing method of claim 23, wherein the another intermediate layer is made of a thermally sprayed film of alumina or a thermally sprayed film of gray alumina.
 25. The manufacturing method of claims 12, further comprising: forming an alumite film on the surface of the base. 